View Full Version : X rails

Dan B. (Unregistered Guest)
03-29-2004, 05:31 AM
I got my Bot on Friday and spent the weekend trying to get the X rails on. I was sure I had it but one wheel on the car rode up on the rail at both ends. The rails as they were shipped are bent and I have been trying to mount them straight. Has anybody had this problem?

03-29-2004, 07:55 AM
Bent in which way Veritcally or horizontally?

And I am sure HopBot will send you new rails if thery are bent.
Call tech support

03-29-2004, 08:26 AM
Permanently bent (sharp kink in one spot) or just flexibly bent (gentle curve along whole length)?

The rails are flexible until you tighten them down on to your table - you must coax them into a straight line, unless they have been permanently kinked.

03-29-2004, 09:48 AM
I remember spending a day or two trying to get mind straight.

03-29-2004, 09:55 AM
Trying getting only one rail dead straight first. Then cut a spacer rod (distance gauge/piece/stick) and use that to get the second rail exactly parallel/equidistant to the first straight rail.

03-29-2004, 10:23 AM
They do take a bit of time to get right, you will go through the same drama with the Y-rails as well. Its worth putting the time in now though.

Erik F.`

03-29-2004, 01:54 PM
Dan - Congratulations on getting your Bot! As noted, it'll take some time to get the rails properly adjusted <sigh>.

Remember that rail parallelism affects wheel centering too - misalignment of one rail can unpredictably affect how the wheels on the opposite car track. You might try leaving one car loosely attached to isolate its effect on the other if you suspect that's a problem.

Your needs might not require this much effort, but I used an extruded aluminum box tube straight edge (10'x2"x3"), feeler gauges, mirror, vernier calipers, and mag-mount dial indicator to get my Bot set up (see other forum threads). Once I got the rails parallel, and close to straight and flat with the feelers, I mounted the cars and used the indicator, mounted to the car, to check for "flat" against the tubing that I placed on the bed rails (parallel to the X axis). I ran the car up and down the X axis and adjust for "flat". And, strangely, the indicator will also tell you if the wheels are centered on the rails because they'll ride vertically up or down the side slope of rails effecting a change on the indicator if they’re not (as you’ve already noticed). If there’s no weight on the car, gently pushing and pulling on it in the Y axis direction will allow you to find the exact center of the wheel track - a push or pull should immediately effect a plus or minus change on the indicator, if not, the wheel’s not centered and is most likely riding up the side of the rail.

Finally, I used the vernier to gauge the rail support washers for thickness – minimizing the need for shims, and the mirror to watch the wheels track on the rails and look for “gapping” (especially Y car wheels).

Anyway, think of the time spent on setup as bonding time with your Bot ; )